Objective：This study aims to observe the effect of curcumin on the biological behavior of rat bone marrow mesenchymal stem cells（rBMSC）. Methods：Complete medium containing curcumin with different concentration gradient was co-cultured with rBMSC. Cell proliferation was detected by CCK-8 method to determine the optimal concentration of curcumin solution. rBMSC were co-incubated with 4 μg/mL curcumin and treated with 0 μg/mL curcumin as control group. The early osteogenic differentiation of rBMSC was evaluated by ALP staining and activity detection. Alizarin red staining was used to evaluate the mineralization of extracellular matrix in late osteoblast differentiation. Real-time fluorescence quantitative reverse transcription PCR was used to detect the expression of bone morphogenetic protein-2（Bmp2），core binding factor alphal 1（Runx2），osteocalcin（Ocn），osteopontin（Opn），and osteo-specific gene（Osterix，Osx）after 7 and 14 days of osteogenesis induction. Results：CCK-8 results showed that rBMSC in culture medium containing curcumin of different concentrations could proliferate continuously，and the promotion effect of 4 μg/mL curcumin on rBMSC was the most significant（compared with the control group，P < 0.001）. ALP activity in curcumin group was higher than that in control group（P < 0.001）. The results of alizarin red staining showed that the extracellular matrix level of curcumin group was higher than that of the control group. The expression of Bmp2，Runx2，Ocn，Opn and Osx in the curcumin group was higher than that in the control group（P < 0.05）. Conclusion：Curcumin can promote the proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells in vitro.